Indwelling central venous catheter infection with Chryseobacterium shandongense – successful eradication in a 5-year-old with cystic fibrosis

Introduction. Chryseobacterium shandongense is a Gram-negative Flavobacterium bacillus with intrinsic multidrug-resistant properties. Case Presentation. Herein, we present the first case report of human C. shandongense infection, relating to an implantable portal and catheter (port-a-cath) central line in a 5-year-old female with cystic fibrosis. The infection was identified using a Bruker MALDI-TOF Biotyper with BDAL (v12) of blood, which was cultured due to pyrexia and rigour following port-a-cath access. This report details the effective eradication of C. shandongense infection from the port-a-cath device using initial empirical gentamicin followed by targeted ciprofloxacin locks and systemic antibiotics. Conclusion. We demonstrated successful eradication of C. shandongense from a port-a-cath device, including the minimum inhibitory concentrations (MICs) required in this case. The result was eradication of central access infection, preventing progression to bacteraemia/septicaemia and preserving central access in a child with cystic fibrosis and established respiratory disease.


INTRODUCTION
There are limited reports of Chryseobacterium spp.infection and human pathogenesis [1].The reports of Chryseobacterium spp.primarily describe Chryseobacterium indologenes (previously Elizabethkingia meningoseptica) infections of young infants, nosocomial infection from indwelling devices and infections in immunosuppressed patients [1].Moreover, to the best of our knowledge, there are no reported cases of Chryseobacterium shandongense causing adult or paediatric infection and, specifically, there are no reported infections of cystic fibrosis (CF) patients.C. shandongense is a Gram-negative bacillus, a non-motile, non-spore-forming and non-fermentative flavobacterium member of the family Weeksellaceae.The human microbiome is not known to include C. shandongense, which is typically detected in freshwater and soil sources [2].Infections associated with Chryseobacterium spp.are described, predominately, as nosocomial from indwelling devices and in immunosuppressed patients with associated high mortality secondary to inherent multidrug resistance [1].This case report describes the successful diagnosis and eradication of C. shandongense infection of an implantable portal and catheter (port-a-cath) device in a 5-year-old female patient with CF through the use of antibiotic locks and systemic antibiotics.

CASE PRESENTATION
A 5-year-old pancreatic-insufficient female with non-modulator-amenable (genotype 1717/1G>A/Q439X) CF required port-a-cath insertion in July 2022 due to established severe upper lobe bronchiectasis requiring regular intravenous antibiotic therapy.Prior sputum cultures demonstrated Streptococcus pseudopneumoniae (January 2018), Moraxella catarrhalis (March 2018), Haemophilus influenzae (May 2019, March 2023), Pseudomonas putida (June 2017, March 2018), Staphylococcus aureus (November 2021, March and November 2022, January and February 2023), Stenotrophomonas maltophilia (September 2023) and Mycobacterium avium complex (February 2023).Her previous cough swabs had repeatedly cultured S. aureus.She had recurring emesis prior to CF respiratory exacerbations.In January 2023, she was admitted, electively, to a regional paediatric CF centre for empirical intravenous antibiotics (ceftazidime and tobramycin) for worsening cough and emesis.Examination revealed widespread crackles and mild intercostal retractions; she was non-coryzal.Her port-a-cath was accessed for antibiotic administration, and within minutes of saline being instilled she developed a pyrexia (38.6 °C) with associated rigours.Thereafter, blood cultures (BACT/ALERT PF Plus) were collected centrally via the port-a-cath and from peripheral venous sites.Empiric peripherally administered ceftazidime (50 mg kg −1 , 8 hourly) and tobramycin (10 mg kg −1 , daily) were commenced intravenously as per local CF antimicrobial guidelines.
Following positive growth signal on the bioMérieux BACT/ALERT 3D instrument, the broth was cultured on solid agar plates for 48 h, with blood and MacConkey plates incubated in air at 35-37 °C, blood agar incubated anaerobically at 35-37 °C and chocolate vancomycin agar incubated in 5-10 % CO 2 at 35-37 %.Following 29 h of incubation at 35-37 o C, the port-a-cath blood cultures returned as positive.Gram-negative bacilli were seen on microscopy.The bacilli were subsequently identified from isolates cultured on nutrient agar as C. shandongense by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) using a BrukerMALDI Biotyper with BDAL (library version 12).This was later confirmed using whole-genome sequencing, again identifying the bacilli as C. shandongense (Fig. 1).Following the initial Gram-negative bacilli result, a gentamicin lock (1.5 ml of 9 mg ml −1 concentration) was commenced into the port-a-cath, as per the manufacturer's volume instructions, for 24 h.Repeat blood cultures were collected from the porta-cath.The peripheral blood cultures remained sterile and no further pyrexia or rigours occurred.The clinical microbiology team were consulted regarding identification and treatment.As the European Committee on Antimicrobial Susceptibility Testing (EUCAST) and Clinical and Laboratory Standards Institute (CLSI) do not publish either breakpoints or consensus epidemiological cut-off (ECOFF) values for Chryseobacterium spp., Table 1 presents antimicrobial susceptibility results using EUCAST pharmacokinetics-pharmacodynamics (non-species-related breakpoints).Following a literature review and local availability, 1.5 ml ciprofloxacin locks were instilled using a 0.125 mg ml −1 concentration, per the port-a-cath manufacturer's volume instructions.
Repeated port-a-cath blood culture, with appropriate discard of instilled antibiotic lock, continued to yield Gram-negative bacilli at 16 h of incubation (45 h from admission), again subsequently identified as C. shandongense.The patient's sputum was sent for microbiological analysis and Chryseobacterium spp.were not cultured.Swabs sent for culture of her nebulizer device were sterile.Investigations on the day of presentation returned a white cell count of 12.8×10 9 (range 5-12×10 9 ), and a C-reactive protein of 21 mg l −1 (normal 0-5 mg l −1 ).As she remained systemically well, this case was likely an isolated port-acath infection without peripheral bacteraemia.Colonization of the line without infection is also possible, but no alternative cause for her pyrexia was identified.Typically, this patient does not develop pyrexia during pulmonary exacerbations of CF.The results were further discussed with the clinical microbiology team.Subsequent paired surveillance blood cultures following 3 and 7 days of antibiotic locks remained sterile.The ciprofloxacin locks were administered for a total of 2 weeks.The patient remained otherwise well and apyrexial throughout the admission.A follow-up port-a-cath blood culture at 6 and 12 weeks post-discharge, at the time of her subsequent routine admissions, yielded no growth and thus successful eradication.

DISCUSSION
There are no descriptions of pathogenic manifestations of C. shandongense cited in the literature to date.We report the first documented case of successful eradication of a C. shandongense intravascular bloodstream infection involving a port-acath.Chryseobacterium-contaminated surgically implanted devices such as central intravenous lines and prosthetic valves have been documented [3].Chryseobacterium indologenes, which shares the same genus, has been shown to cause severe, invasive infections, especially in patients with risk factors such as indwelling devices, immunosuppression and a history of prolonged courses of broad-spectrum antibiotics [3].The prevalence of C. indologenes has been increasing in recent years, and infections have been associated with an overall mortality rate, in small case series (n=16), of 17-28 % [4].This series showed 63.6 and 35.2% mortality rates in those patients specifically with C. indologenes bacteraemia and pneumonia, respectively [4].Patients with CF potentially have multiple risk factors, such as indwelling devices, which could put them at greater risk for Chryseobacterium species-associated infection.Therefore, recognition of this bacterium and its subsequent treatment are essential for reducing mortality risk.Sputum isolates of Chryseobacterium spp.from patients with CF have been demonstrated [5,6].Additionally, when detected in sputum samples, Chryseobacterium spp.were not associated with a decline in pulmonary function and mortality [5,6].Considering the limited data available regarding Chryseobacterium spp., further studies are essential to fully understand their clinical significance in CF.
Notably, Chryseobacterium spp.are reported to be multidrug-resistant organisms, posing challenges for antibiotic choice and treatment options [7].Additionally, their intrinsic multidrug resistance contributes to the high mortality, as described above.The agents typically deployed to treat non-fermenting bacteria are expected to remain effective, such as meropenem, ciprofloxacin, aminoglycosides and piperacillin-tazobactam. Information regarding Chryseobacterium susceptibilities in vitro remains relatively sparse, as the species has rarely been isolated clinically [8,9].Literature reports suggest that the species is frequently resistant to a wide range of antibiotics, including penicillins, first-, second-and third-generation cephalosporins, and monobactams such as aztreonam.The limited literature available at the time of this report suggests that the most effective The Microbiology Society is a membership charity and not-for-profit publisher.
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1-In line 40, please cite the relevant references for "There are limited reports of Chryseobacterium spp infection and human pathogenesis."
-Reference 1 cited within text now line 42.

2-
The sentences should begin with complete words, not abbreviations; for the name of bacteria, please write the complete form ( genus and species ) at the beginning of the sentence.For example, in line 45, please replace "Chryseobacterium shandongenes" instead of "C.shandogenes".
-Amended in the text where appropriate.

3-In line 48, the author mentioned,"
Infections associated with C. spp are described…" What is the meaning of C.spp.please correct this section.
-"C. spp" in this case referred to "Chryseobacteriumspecies". This has been amended in the text where appropriate.
4-In line 67, the authors mentioned:" blood cultures were collected centrally".Please add the information on the method of culturing " BACTEC.The type of bottle?Also, the variety of media for culture.
-Details have been added to the text regarding this comment.Between lines 76-84.
"Thereafter, blood cultures (BACT/ALERT PF Plus) were collected centrally via the port-a-cath and from peripheral venous sites.Empiric peripherally-administered ceftazidime (50mg/kg, 8 hourly) and tobramycin (10mg/kg, daily) were commenced intravenously as per local CF antimicrobial guidelines.Following positive growth signal on the Biomerieux BACT/ALERT 3D instrument, the broth was cultured on solid agar plates for 48 hours, with blood and MacConkey plates incubated in air at 35-37 o C, blood agar incubated anaerobically at 35-37 o C and chocolate vancomycin agar incubated in 5-10% CO2 at 35-37%.
5-In line 71, the author mentioned," Following 29 hours of incubation," please write the incubator's temperature".-Unfortunately, there is no available literature to date on cases of Chryseobacterium shandogenseas a cause of infection.Therefore it is not possible to make a table as described above.There is currently clinical information regarding Chryseobacterium indologenes, however a table for this species would not be relevant given as it was not the bacteria is not the focal point of the case.

6-I
Response to Reviewer 2 Comments to Author:

Presentation of results
A case report therefore no results.However the antibiotic sensitivities are unclear.

How the style and organization of the paper communicates and represents key findings
The paper is appropriately split into introduction, case report and discussion helping to delineate each part.Regarding the events occurrence I would keep this chronologically or create a timeline of events as there is some jumping around which can be confusing to read ie Porta cath placed 2022, then PEG placed in 2019, admitted in 2023.
-Restructured as suggested above.

Literature analysis or discussion
The literature review cover relevant papers.The discussion fails to mention why the team decided to try and salvage the line rather than just remove it.I appreciate the patient needs frequent antibiotics but I think it would be worth commenting on the clinical rationale of the decision.
-Answered this question in line 177-179."Additionally, salvage as opposed to removal of the port-a-cath was attempted due to prior difficult access and an ongoing requirement for regular intravenous antibiotics."

Any other relevant comments
There are spelling errors throughout the paper related to the primary organism.The organism varies between shandogenes or shandongenes, however when reviewing other literature I believe the organism is actually named Chryseobacterium shandongense.Therefore this will need changed throughout the manuscript including in the title.Please also avoid the use of abbreviations unless this is described or explained within the text ie.Line 45 people with CF (pWCF).It is the first time mentioning CF and therefore should be written as Cystic Fibrosis (CF).There should also be terminology consistency ie Chyrseobacterium spp, Chyrseobacterium species & C.spp all get used interchangeably throughout.
-The spelling errors have been amended throughout the text to "Chryseobacerium shandongense".When discussing the species mention we first as Chryseobacterium shandongenseand in subsequent mentions as C. shandongense(with use of italics) When referring to the genus Chyrseobacterium we used terminology "Chyrseobacterium spp".
With regards to the MICs used, there is no indication where these breakpoints are from as I believe there are no EUCAST or CLSI Chyrseobacterium spp breakpoints.
-Referenced from line 105 to 115.Table included with minimum inhibitory concentrations of antibiotics tested against C.shandongense.
I note other papers have used both Pseudomonas and non Enterobacteriaceae breakpoints.I would clarify which breakpoints were used and rationale behind this.Microbiological images of growth on agar or microscopy would also be useful as this is the first case report of a line infection.
-Unfortunately images of growth on agar or microscopy are not available.
There are some other small amendments I would suggest which helps to clarify ambiguity.Line 63 mentions that the patient was 'admitted empirically'.I presume they were admitted for empirical antibiotics and were either admitted electively or as an emergency.Can this please be clarified?Line 66/67 it is written that blood cultures were taken 'peripherally and centrally.'It is never specifically mentioned that cultures were taken from the port-a-cath.As this is the crux of the paper I would specifically mention this.
-Changed to collected centrally via port-a-cath (line 77) Line 91/92 states that Chryseobacterium was not grown in the sputum.Was any other bacteria grown and in the context of her CF and recurrent chest infections was this treated/influence the clinical course?Date report received: 18 October 2023 Recommendation: Minor Amendment Comments: 1. Description of the case(s) Interesting case report describing the first reported case of a Chryseobacterium shandongense line infection in a Cystic fibrosis patient.2. Presentation of results A case report therefore no results.However the antibiotic sensitivities are unclear.The MICs are demonstrated in the body of the text but it is unclear what the interpretation of the MICs are i.e. are they susceptible/resistant/susceptible at increased dose.This could be demonstrated in a table format.3. How the style and organization of the paper communicates and represents key findings The paper is appropriately split into introduction, case report and discussion helping to delineate each part.Regarding the events occurrence I would keep this chronologically or create a timeline of events as there is some jumping around which can be confusing to read ie Porta cath placed 2022, then PEG placed in 2019, admitted in 2023.4. Literature analysis or discussion The literature review cover relevant papers.The discussion fails to mention why the team decided to try and salvage the line rather than just remove it.I appreciate the patient needs frequent antibiotics but I think it would be worth commenting on the clinical rationale of the decision.5. Any other relevant comments There are spelling errors throughout the paper related to the primary organism.The organism varies between shandogenes or shandongenes, however when reviewing other literature I believe the organism is actually named Chryseobacterium shandongense.Therefore this will need changed throughout the manuscript including in the title.Please also avoid the use of abbreviations unless this is described or explained within the text ie.Line 45 people with CF (pWCF).It is the first time mentioning CF and therefore should be written as Cystic Fibrosis (CF).There should also be terminology consistency ie Chyrseobacterium spp, Chyrseobacterium species & C.spp all get used interchangeably throughout.With regards to the MICs used, there is no indication where these breakpoints are from as I believe there are no EUCAST or CLSI Chyrseobacterium spp breakpoints.I note other papers have used both Pseudomonas and non Enterobacteriaceae breakpoints.I would clarify which breakpoints were used and rationale behind this.Microbiological images of growth on agar or microscopy would also be useful as this is the first case report of a line infection.There are some other small amendments I would suggest which helps to clarify ambiguity.Line 63 mentions that the patient was 'admitted empirically'.I presume they were admitted for empirical antibiotics and were either admitted electively or as an emergency.Can this please be clarified?Line 66/67 it is written that blood cultures were taken 'peripherally and centrally.'It is never specifically mentioned that cultures were taken from the port-a-cath.As this is the crux of the paper I would specifically mention this.Line 91/92 states that Chryseobacterium was not grown in the sputum.Was any other bacteria grown and in the context of her CF and recurrent chest infections was this treated/influence the clinical course?Line 101/102.The discussion mentions that treatment was for 2 weeks but I think this should be stated in the case report itself.Also clarify regarding which antibiotics were given for this duration

Please rate the quality of the presentation and structure of the manuscript Good
To what extent are the conclusions supported by the data?Strongly support

Is there a potential financial or other conflict of interest between yourself and the author(s)? No
If this manuscript involves human and/or animal work, have the subjects been treated in an ethical manner and the authors complied with the appropriate guidelines?Yes

Fig. 1 .
Fig. 1.Visualization using the Krona tool of the metagenomic classification of 13 000 reads from the C. shandongense isolate, following read assignment by the original BugSeq algorithm.

Table 1 .
Table demonstrating the antibiotic minimum inhibitory concentrations (MICs) in mg l −1 and sensitivity (S) or resistance (R) for C. shandongense cultured centrally via the patient's port-a-cath are quinolones and trimethoprim-sulfamethoxazole, with 95 % of isolates susceptible[9].Duration of therapy in most cases is 7-14 days.Ultimately, treatment should be tailored with results of antibiotic susceptibility tests and assessment of the patient's clinical response.In this case, we have demonstrated that effective eradication from a port-a-cath can be achieved with appropriate antibiotic locks through the use of both gentamicin (for 24 h) and ciprofloxacin for 2 weeks.Additionally, salvage as opposed to removal of the port-a-cath was attempted due to prior difficult access and an ongoing requirement for regular intravenous antibiotics.Herein, we demonstrated successful eradication of C. shandongense from a port-a-cath device, including the MICs required in this case.The result was eradication of central access infection, preventing progression to bacteraemia/septicaemia and preserving central access in a child with CF and established respiratory disease.
suggest the author add a table and list the Cases of infections caused by Chryseobacterium shandongenes reported in the literature ( age, gender, type of infection, Country, Underlying condition, predisposing factors, treatment regime, and outcomes. The MICs are demonstrated in the body of the text but it is unclear what the interpretation of the MICs are i.e. are they susceptible/resistant/susceptible at increased dose.This could be demonstrated in a table format.-Replaced the line -"Ciprofloxacin, Ceftazidime and Gentamicin of 0.25mg/L, 2mg/L and 3mg/L respectively" with "As EUCAST and CLSI do not publish either breakpoints or consensus ECOFF values for Chrysobacterium spp, Table1presents antimicrobial susceptibility results using EUCAST PK-PD (non species related) breakpoints, Clinical Breakpoint Tables v. 13.0)" and the following table.